-aluminum sulphate



Patented Oct. 17, 1933 lUN-1TED1 T A PATENT! i is-E MANUFACTURE OFALCOHOLS Ann A UMINUM SULPHATE v William 'SLWilson, Boston, Mass,assignor to Merrimac Chemical Company, Inc., Everett, Mass, acorporation of Massachusetts V No Drawing.

Application November 29, 1932 v Serial lf lo. 6l4, 8 v

- ,6 Claims. (oi. 23-124)" This invention relates to the 'manufacture ofalum (aluminum sulphate) from bauxite or calcined clay and it'ischaracterizedinthat alcoholis obtained as a by-product of the process. I

Alum is manufactured by reacting. bauxite with sulphuric'acidun'der'conditions whereby a solution containing, 8-9%,.

readily filterable A1203 is obtained; The bauxite employed is theordinary bauxite of commerce which contains 5'20% of acidinsoluble:matter consisting essentially of silica, silicates, etc., After thereaction tion ofwater whereby ethyl alcohol isformedand sulphuric acidin dilute condition is recov-, 25.

after which the acid must be concentrated in (approximately 40%) whichisnecessitated by reason of the tendency under more acid condi-=*formation is to a certain extent a function of the purity of theethylene, temperature of the absorpbetween, the'bauxite and the acid iscompleted the mixture is filtered or decanted to recover the clear alumsolution from the residue. The solution is then evaporated toapproximately 17.3% A1203. v

It is'knownthat sulphuric acid reacts with an olefine, in the case ofethylene, to form diethyl sulphate;

moderately elevated temperatures by theaddi- ,eredj The alcohol isseparated by distillation order that it may be utilized again in theabsorption of more ethylene. Thisprocedure has certain objections. Thusfor example, the acid ob.- tained as a result of the hydrolysis is verydilute tions toward partial hydrolysis and consequent diethyl,ethenform'ation. Furthermore, ethylene polymers, higher homologues andother impuri ties which undergo decomposition in the the course of theabsorption and which remain in the acid in the form of tars and darkcolored carbonaceous impurities. The amount of tar tion, conditions ofthe hydrolysis, as well as other factors. However, even under goodcommercial eondition it is impractical to eliminate these impurities inthe acid which not only interferes with the efficiency of a cyclicabsorption and hydrolysis operation but also causes a reduction andconsequent loss of the sulphuric acid during the concentrationoperations.

According to the present invention the dilute (40-70%) contaminated acidresulting from the hydrolysis of the ethyl esters of sulphuric acid isheated to 175--200 C. for a few minutes whereby the impurities arerendered separable in the Heretofore it has been proposed to hydrolyzethe ethyl sulphate ester mixture thus obtained at is commonly associatedwith varying amounts of subsequentlstep and thereafter is reacted withbauxite. Thus one obtains a'filterable solution of. alum in whichthecarbonaceous, tar-likeimpurities are readily 'and completely absorbedon the siliceous residue. In this conditionthe acid k insolubleimpurities, including the tar-like impurity, may be filtered orotherwise separated from-the clear alum solution that upon evaporationproduces without further purification a commercial grade of alum.Obviously, if desired,

the acid may be concentrated and usedseveral times before it is reactedwith bauxite. The sulphuric, acid heat treatment may be effectedconveniently in an autoclave; the precise temperature condition need notbe adhered. to '70 nor is the period of heating inflexible. When thetemperature of the acid is raised to 175-200 C. the more or lesscolloidal carbonaceous impurities undergo a rapid change whereby theymay be adsorbed or otherwise eliminated from their state. I

Alternatively, one may effect the hydrolysis of suspended .[andotherwise difficultly separable the ethylsulphate esters'irf'thepresence of suspended bauxitein, water orjweak alum solution whereby thehydrolysis reaction proceeds under acidic conditions, completelyandsatisfactorily at -a substantially higher concentration, withoutether'Iformation than possiblein the absence of the bauxite. As aresult, the alum solution which is produced is relatively moreconcentrated and the cost --of evaporation isreduced correspondingly. r

Although the present invention is particularly into the correspondingalcohols such as propylene and butylene by a procedure analogous to thatset forth above and described morefully hereine 154 pounds of the ethylsulphate esters, having a composition substantially as outlined above,are added slowly to a suspension of 40 pounds ofbauxite in 225 pounds ofwater. The suspension is refluxed during the addition of thesulphatereagent. After all the reagent has F 'Well suited to themanufactureof ethyl alcohol from ethylene. it may likewise be. appliedto the conversion of other normally gaseous olefines,

7 been added, the refluxing is continued for a short period of time inorder to complete the reaction and thereafter the alcohol is distilledfromithe mixture. The remaining traces of alcohol which are noteliminated 'readily by simple distillation may be removed by forcingsteam through the charge. Thereafter- 20, pounds of bauxite are added tothe acid mixture which reacts with the free acid to produce an 8.5 to 9%A1203 solution of 10 basic alum. The iron which 'is present in thesolution. is then reduced in the usual manner after which the alumsolution is filtered free of the insoluble residue. The solution is thenevap orated until it contains approximately 17.3%

A1203; Theyield of alcohol as well as aluminum sulphate is practicallyquantitative.

It .is to be understood that one may employ ethylene in which case thealcohol productflrecovered is pure ethyl alcohol. On the other hand,

6 if desired, one may employ a mixtureof olefines whereby one obtainsafmixture of alcohols.v

- Thus, for example, propylene is absorbed by sul-Y phuric acid to formthe propyl hydrogen sulphate and dipropyl sulphate, which upon.hydrolysis yields isopropyl alcohol. Similarly, butylen'e yieldssecondary ortertiar'y-butyl alcohol; Mix ture's' ofjthe olefines willproduce mixtures of alcohols. In general, however, I 'pre'ierjto ,sep

;-.arate or fractionate the olefines first and thereby limit the alcoholproduct, to a; single alcohol.

This is unnecessary, of'courseand one may first form .a mixture ofalcohols and then effect the separation if required by the usualmethods, for example, byfractionation. ,'Obviously, if desired,the'amount of water in which the bauxite is suspended may be reduced or]increased whereby the concentration of the resulting alumsolution iscorrespondingly increased.or -.decreased. Similarly, one may hydroliaethe ethyl ""sulphate esters practically completelyin the absence orbauxite, after which bauxite is added to the aqueous sulphuricacidsolutioncontaining the tar-like and other suspended and] dissolved,-impu'r ities. Althoug'hjl prefer to hydrolyzethe organic sulphatesunder conditionswhich insure an excessof acid,particularlyf'duringthelatter' stages of the-hydrolysis, sincehndettheseconditions, thehydrolysis has been ,found' to bemore rapidyand complete, neverthelessone ay in:- trodiucejall of the bauxiteatithe'outsetitde- S1re a, 7 v

It is to be understobdthat{the ai -1a drbauxite maybe varied accordingto thefamount of' sulphatewhichfis p'resentlinf the ethyl sul- 5phatemixture which in turnis dependenton the conditions ofthe'absorption. One may deter mine the amount of sulphate present,conyen-f in this manner.

obtained by the inter-action of sulphuric acid and ethylene.)

pleting thehydrolysiswhile maintaining an acid iently, by hydrolyzing arepresentative weighed sample-of the sulphate ester following in generalthe procedure outlined in the process and determining the'quantity ofalcohol by distilling the amount of' sulphateain the aqueous solutionafter hydrolysis. The amount of ethyl sulphate and diethyl sulphate maylikewise be ascertained From theforegoing description it will be apparent that I have discovered a method of producing, alum wherein ethylalcohol is obtained as a by-product. It will likewise be apparent thatthe invention affords a convenient Way of disposing of the acid which iscontaminated with carbonaceous and tar-like impurities that wouldotherwise accumulate in the acid in the course of its .use as anabsorbing medium for ethylene and further that the method enables one tore- -duce ether formation and at the same time offeet completehydrolysis oithe ester to the corresponding alcchol While avoiding to alarge extent the dilutionof the ester as is necessary in the absence ofthe. bauxite treatment,

' ester is that obtained by the inter-action of sulphuric acid and atleast one olefine selected'from a group consisting oi the following;ethylene, propylene, and butylene;

3. The method as definedin claim l and further characterized in that thealkyl ester is that 4.'The method which comprises hydrolyzing 'alkylsulphate esters in the presence of bauxite and'water. I p 5. The methodwhich comprisesat least partially hydrolyzing with water an alkylsulphate ester, adding bauxite to the resulting mixture" wherebyaluminum sulphate is formed, and comcondition. 7 7 4 V 6; 'I'he'methodas. definedin claim 5 and-further characterized in tha-tadditionalbauxite-is added to "the completelyhydrolyzed mixture to convert thefree acid present therein t'o'aluminum sulphate. Y

; 1 WILL MS. WILSQN.-

